Clutch assemblies are generally known in the transportation industries and are used to couple an engine to an input of a transmission for providing motion to a vehicle, such as a motorcycle. A typical clutch couples an engine crank shaft to an input shaft of the transmission by using numerous spring loaded friction disks, or plates. Some of the disks are mechanically coupled to the input shaft of the transmission, while other disks are coupled to the engine crank shaft via a gear mechanism, or the like. The transmission input shaft rotates in response to rotation of the engine crank shaft when the friction disks are compressed together. To decouple the input shaft of the transmission, a compression force is removed from the friction disks such that friction between adjacent disks is reduced.
To remove or reduce the compression on the clutch disks, a clutch release mechanism is typically provided. In a motorcycle application, the release mechanism is activated using a clutch lever attached to the motorcycle handle bars. The clutch lever is attached to the clutch released mechanism using either a cable or a hydraulic line. While cables can provide satisfactory operation, numerous problems can be experienced over the lifetime of the vehicle, such as broken, stretched, and stuck cables. Therefore, hydraulic activation is often preferred which reduce or eliminate these types of problems.
Hydraulic clutch systems work by using a master cylinder, which contains hydraulic fluid, to force a predetermined amount of hydraulic fluid into the release mechanism via a hydraulic line. A typical hydraulic clutch release mechanism operates by moving a push rod which extends through the center of a transmission input shaft. The push rod pushes on the clutch to relieve compression applied to the clutch disks. This requires that the clutch release mechanism be located on an opposite side of the transmission than the clutch itself. Thus, the transmission is located between the release and the clutch. This application can be difficult to implement in motorcycles which use a rear wheel belt drive system. That is, an output shaft of the transmission, in combination with a rear wheel drive pulley, may not leave sufficient room for a hydraulic release mechanism which pushes a rod through the input shaft to release the clutch.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a hydraulically activated clutch release mechanism which can be located adjacent to the clutch disks and does not require a push rod.